The laboratory task of effortless and immediate perceptual segregation between regions of visual texture may be a good model f an important stage in everyday visual perception -- a state at which the visual system breaks a visual scene into meaningful regions before going on to do further computations on each region. An understanding of the visual processes controlling the perceived segregation among regions may be gained by building on the vast amount of knowledge that has accrued over the last several decades about relatively low-level visual processes. Results from psychophysical experiments measuring perceived texture segregation (and several related perceptual tasks) will be collected. These empirical results will be compared to predictions from quantitative models based on current knowledge about low-level visual processes. These quantitative models will incorporate knowledge about pattern-vision analyzers (multiple analyzers acting in parallel that are selectively sensitive to spatial frequency, orientation, and spatial position -- the physiological substrate for which may be in the lowest areas of visual cortex) and also about the manifest nonlinearity studied under the name light adaptation (and probably of retinal origin) as well as some nonlinear behavior now known to be characteristic of cortical cells.